The results as regards time of clinical union in 395 cases of fracture of the tibia and fibula in adults have been analyzed. The conclusions drawn are as follows:

1. There has been an increase in the incidence of delayed union during this War.

2. This is noticed mainly in the newly established clinics.

3. The increase is seen in both simple and compound fractures.

4. In the greater number of compound fractures, "disturbance" of the course of treatment and the use of continuous skeletal traction appear to be the chief factors causing this increase. Most of these factors are preventable.

5. Manual reduction and the application of a long padded plaster cast is the method of choice in the treatment of simple fractures, from the point of view of speed of union.

6. The merits of bone-grafting and of the application of the walking caliper in cases where delayed union is present are discussed. It is considered that the results in this series establish prima facie evidence for the use of the walking caliper in selected cases.

7. Certain points, for example, the high incidence of delay in compound fractures at the junction of the lower and middle thirds of the tibia, the effect of the severity of the fracture, the effect of early or late weight-bearing, and the merits of early operation in cases where difficulty is experienced in reduction, require further investigation.